This invention relates to manhole covers for tanker cars, and in particular, to an automatic manhole cover.
Manhole covers are known for providing an inlet into a structure, such as a trailer tanks which hold particulate matter (i.e., grain, plastic pellets, flour, cement, sugar, etc.) as well as liquids.
The manhole covers typically provided on rail road tankers and truck trailers are manually operated covers. They include a series of cam operated levers which surround the manhole cover and are operable to lock and unlock the cover. To open and close prior manually operated manhole covers, someone must climb onto the tanker using a ladder at the back of the tanker. Then, he must walk along a catwalk which extends the length of the tanker until he reaches the manhole cover. To reach the manhole cover, and to provide enough leverage to operate the locks, the worker must step on the tanker shell itself. Working on top of a tanker can be precarious and exposes the worker to a risk of falling. The risk of falling increased if the tanker is wet or icy.
Further, the manual locks which hold the tank cover closed can be difficult to open. Again, the difficulty in opening the tank cover can be increased if the locks are, for example, frozen. This difficulty in operating the manual locks can increase the risk of falling.
Thus, it is desirable to not only make manhole covers easier to open and close, but to enable workers to remotely open and close manhole covers (i.e., from the ground).